JP6598474B2 - Silane-crosslinkable rubber composition, silane-crosslinked rubber molded article, production method thereof, and silane-crosslinked rubber molded article - Google Patents

Description

  The present invention relates to a silane cross-linkable rubber composition, a silane cross-linked rubber molded article, a production method thereof, and a silane cross-linked rubber molded article.

Coating materials for various industrial cables (including electric wires), rubber molding materials (among others, automotive rubber molding materials, such as automotive glass run channels, weather strips, rubber hoses, wiper blade rubber, anti-vibration rubber) or gaskets, etc. These rubber products are required to have a low compression set. Of the various industrial cable coating materials, the cabtire cable insulating material and the like are preferably materials having both flexibility and tensile strength from the viewpoint of cable handling.
Conventionally, a crosslinked EP rubber obtained by vulcanizing (crosslinking) ethylene-propylene rubber (EP rubber) has been used for products used for applications requiring a small compression set. However, the crosslinked EP rubber had to be vulcanized after the EP rubber was molded.
In Patent Document 1, in the method of injection molding a rubber composition mainly composed of ethylene-propylene rubber, the propylene content is 30 to 55% by weight as the above-mentioned ethylene-propylene rubber, Mooney viscosity (ML1 + 4 (100 ° C.)) Has been proposed to add organic peroxide as a vulcanizing agent. In Patent Document 2, it has been proposed to further subject a vulcanized rubber product to a thermal history treatment under atmospheric pressure or vacuum pressure. In Patent Document 3, the rubber contains 100 parts by mass of rubber and 30 parts by mass to 150 parts by mass of metal hydroxide, and the rubber has an ethylene ratio of 60% to 64% and an ethylene ratio of 66% to 66%. A non-halogen flame retardant rubber composition in which 70% ethylene-propylene rubber 2 is mixed at a mass ratio of 70:30 to 30:70 has been proposed.

JP-A-8-66931 JP-A-11-302415 JP 2012-241041 A

In each of Patent Documents 1 to 3, a vulcanization process for heating and vulcanizing rubber is required in production, and therefore a vulcanization facility that can be heated to a temperature at which the rubber is vulcanized is necessary. In addition to this, the vulcanization time is long and there is a problem in productivity.
Further, when a general EP rubber is used to obtain a product having excellent flexibility (low hardness), a material having a low Mooney viscosity and a low ethylene content is often used. However, such a material has a problem of inferior tensile strength.

The present invention provides a silane-crosslinked rubber molded article that overcomes the above-described conventional problems, has both excellent flexibility and high tensile strength, has a small compression set, and has an excellent appearance, and a method for producing the same. Is an issue.
The present invention also provides a silane crosslinkable rubber composition and a method for producing the same, which can produce the silane crosslinked rubber molded product having the above-mentioned characteristics with high productivity without requiring a vulcanization facility. Let it be an issue.
Furthermore, this invention makes it a subject to provide the silane crosslinked rubber molded article containing the silane crosslinked rubber molded object which has said outstanding characteristic.

In the production of a crosslinked rubber molded body using EP rubber, the inventors of the present invention need no vulcanization equipment for EP rubber and use a silane coupling agent as a raw rubber. It was found that a silane-crosslinked rubber molded article having a high tensile strength, a small compression set and an excellent appearance can be obtained without impairing its flexibility even when using a low EP rubber. Based on this finding, the present inventors have made further studies and have come up with the present invention.
Here, the rubber silane cross-linking method refers to a silanol condensation catalyst after a hydrolyzable silane coupling agent having an unsaturated group is grafted to rubber in the presence of an organic peroxide to obtain a silane-grafted rubber. In this method, the silane graft rubber is brought into contact with moisture to obtain a crosslinked rubber in which the silane graft rubber is crosslinked through a silane coupling agent.

That is, the subject of this invention was achieved by the following means.
[1] An ethylene-α-olefin having a Mooney viscosity (ML (1 + 4) 125 ° C.) measured in accordance with JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of 45% by mass or more and less than 65% by mass. 1 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of grafting to the base rubber and a reaction site capable of silanol condensation with respect to 100 parts by mass of the base rubber containing 70 to 100% by mass of rubber. Silane crosslinkable rubber grafted at a grafting rate of 70 to 100% by mass, and 100 to part by mass of the base rubber, 0.3 to 150 parts by mass of an inorganic filler, and 0.0001 to 0.5 of a silanol condensation catalyst. A silane crosslinkable rubber composition containing a part by mass.
[2] The silane crosslinkable rubber composition is capable of silanol condensation with 0.3 to 150 parts by mass of an inorganic filler, a grafting reaction site capable of grafting to the base rubber, and 100 parts by mass of the base rubber. 1 to 15 parts by mass of a silane coupling agent having various reaction sites, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.0001 to 0.5 parts by mass of a silanol condensation catalyst The silane crosslinkable rubber composition according to [1], wherein the base rubber and the silane coupling agent are grafted.
[3] The silane crosslinkable rubber composition according to [1] or [2], wherein the inorganic filler is at least one selected from the group consisting of metal hydrate, talc, clay, silica, and carbon black.
[4] The silane crosslinkable rubber composition according to any one of [1] to [3], wherein the base rubber includes 1 to 30% by mass of a polypropylene resin.
[5] The silane crosslinkable rubber composition according to any one of [1] to [4], wherein the content of the silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the base rubber. .
[6] A silane-crosslinked rubber molded product obtained by molding the silane-crosslinkable rubber composition according to any one of [1] to [5] and then condensing the reaction site capable of silanol condensation .
[7] A silane-crosslinked rubber molded product comprising the silane-crosslinked rubber molded product according to [6].
[8] An ethylene-α-olefin having a Mooney viscosity (ML (1 + 4) 125 ° C.) measured in accordance with JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of 45% by mass or more and less than 65% by mass. With respect to 100 parts by mass of the base rubber containing 70 to 100% by mass of rubber, 0.3 to 150 parts by mass of an inorganic filler, a grafting reaction site capable of grafting to the base rubber, and a reaction site capable of silanol condensation 1 to 15 parts by mass of a silane coupling agent, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.0001 to 0.5 parts by mass of a silanol condensation catalyst are melt-mixed, and the base rubber Silane cross-linking having the step (1) of obtaining a silane cross-linkable rubber composition containing a silane cross-linkable rubber by grafting reaction with the silane coupling agent. A method for producing a conductive rubber composition, comprising:
In carrying out the step (1), when all of the base rubber is melt-mixed in the following step (a), the step (1) has the following step (a) and step (c). In the case where a part of the base rubber is melt-mixed in (a), the production of the silane crosslinkable rubber composition, wherein the step (1) has the following steps (a), (b) and (c): Method.
Step (a): All or part of the base rubber, the inorganic filler, and the silane
The pulling agent and the organic peroxide are separated from the decomposition temperature of the organic peroxide.
The base rubber and the silane coupling agent are melt mixed at the above temperature
And a silane containing a silane crosslinkable rubber
Step of preparing a master batch Step (b): Melt and mix the remaining base rubber and the silanol condensation catalyst
Step of preparing a medium master batch Step (c): The silane master batch and the silanol condensation catalyst or the catalyst matrix
Step 9 is a method for producing a silane-crosslinked rubber molded article having the following step (1), step (2) and step (3) to melt and mix a star batch to obtain a silane crosslinkable rubber composition,
Step (1): Mooney viscosity measured based on JIS K 6300-1: 2013
(ML (1 + 4) 125 ° C.) is 15 to 40, and the ethylene content is 4
70% of ethylene-α-olefin rubber that is 5% by mass or more and less than 65% by mass
0 to 100 parts by mass of base rubber containing 100% by mass of inorganic filler 0
. 3 to 150 parts by mass and graph capable of grafting reaction to the base rubber
Silane cup having a reaction site and a reaction site capable of silanol condensation
1 to 15 parts by mass of a ring agent, 0.01 to 0.6 parts by mass of an organic peroxide,
The silanol condensation catalyst 0.0001 to 0.5 part by mass is melt mixed and
The base rubber and the silane coupling agent can be grafted.
Step of obtaining a silane crosslinkable rubber composition containing a silane crosslinkable rubber Step (2): Molding the silane crosslinkable rubber composition obtained in the step (1) to obtain a molded body.
Step (3): Silane cross-linked rubber molding by contacting the molded body obtained in the step (2) with water.
The process of obtaining the body

In carrying out the step (1), when all of the base rubber is melt-mixed in the following step (a), the step (1) has the following step (a) and step (c). In the case where a part of the base rubber is melt-mixed in (a), the production of the silane crosslinkable rubber composition, wherein the step (1) has the following steps (a), (b) and (c): Method.
Step (a): All or part of the base rubber, the inorganic filler, and the silane
The pulling agent and the organic peroxide are separated from the decomposition temperature of the organic peroxide.
The base rubber and the silane coupling agent are melt mixed at the above temperature
And a silane containing a silane crosslinkable rubber
Step of preparing a master batch Step (b): Melt and mix the remaining base rubber and the silanol condensation catalyst
Step of preparing a medium master batch Step (c): The silane master batch and the silanol condensation catalyst or the catalyst matrix
A process of obtaining a silane crosslinkable rubber composition by melt mixing with a star batch

  In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

According to the present invention, a silane-crosslinked rubber molded article that overcomes the above-described conventional problems, achieves both excellent flexibility and high tensile strength, has a small compression set, and has an excellent appearance, and a vulcanization facility for EP rubber. It is not necessary and can be manufactured with high productivity.
Therefore, according to the present invention, it is possible to provide a silane-crosslinked rubber molded article having both excellent flexibility and high tensile strength, small compression set, and excellent appearance, and a method for producing the same. Further, it is possible to provide a silane cross-linkable rubber composition that can produce a silane cross-linked rubber molded article having such excellent characteristics without vulcanization equipment and with high productivity, and a method for producing the same. Furthermore, a silane cross-linked rubber molded article including the silane cross-linked rubber molded article having such excellent characteristics can be provided.

The silane crosslinkable rubber composition of the present invention has a Mooney viscosity (ML (1 + 4) 125 ° C.) measured based on JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of less than 45 to 65% by mass. A silane crosslinkable rubber obtained by grafting a silane coupling agent to a base rubber containing 61 to 100% by mass of ethylene-α-olefin rubber, and 0.3 to 150 parts by mass of an inorganic filler with respect to 100 parts by mass of the base rubber. And 0.0001 to 0.5 parts by mass of a silanol condensation catalyst. This silane crosslinkable rubber composition is preferably 0.3 to 150 parts by mass of an inorganic filler, 1 to 15 parts by mass of a silane coupling agent, and 0.01 to an organic peroxide with respect to 100 parts by mass of the base rubber. It can be prepared by melt mixing ˜0.6 parts by mass and 0.0001 to 0.5 parts by mass of silanol condensation catalyst. Thereby, as will be described later, the silane coupling agent is grafted to the base rubber to form a silane crosslinkable rubber.
The silane cross-linked rubber molded product of the present invention can be obtained by molding the silane cross-linkable rubber composition of the present invention and then bringing it into contact with water. Thereby, as described later, the silane coupling agent of the silane crosslinkable rubber contained in the silane crosslinkable rubber composition undergoes a crosslinking reaction to form a silane crosslinked rubber molded product.

First, each component used for this invention is demonstrated.
<Base rubber>
The base rubber used in the present invention has a Mooney viscosity (ML (1 + 4) 125 ° C.) of 15 as a rubber component having a site where the silane coupling agent can be grafted and measured according to JIS K 6300-1: 2013. The ethylene-alpha olefin rubber which is -40 and ethylene content is less than 45-65 mass% is contained.
The base rubber may further contain a polypropylene resin.
The base rubber may further contain a rubber component other than the ethylene-α olefin rubber and a resin component other than the polypropylene resin. The rubber component other than the ethylene-α-olefin rubber is not particularly limited. For example, natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylic rubber (ACM), silicone rubber (Q). Etc. The resin component other than the polypropylene resin is not particularly limited, and examples thereof include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and an ethylene copolymer. . When the base rubber contains these rubber component and resin component, the contents of these rubber component and resin component are not particularly limited, and are appropriately determined.
In this base rubber, the content of each rubber component and each resin component is appropriately determined so that the total amount of the rubber component and the resin component is 100% by mass, and is preferably selected from the following range.

(Ethylene-α olefin rubber)
The ethylene-α olefin rubber used in the present invention has a Mooney viscosity (ML (1 + 4) 125 ° C.) measured based on JIS K 6300-1: 2013 of 15 to 40, and an ethylene content of less than 45 to 65% by mass. This is an ethylene-α-olefin rubber. If the Mooney viscosity is too small, the tensile strength may be insufficient. On the other hand, if the Mooney viscosity is too large, the flexibility may be inferior. Further, if the ethylene content is less than 45% by mass, the tensile strength may be insufficient. When the ethylene content is 65% by mass or more, flexibility may be inferior.
The Mooney viscosity of the ethylene-α-olefin rubber is preferably 15 to 40 (ML1 + 4 (125 ° C.), more preferably 17 to 35 (ML1 + 4 (125 ° C.)) in terms of tensile strength and flexibility. (ML1 + 4 (125 ° C.) is more preferable.
Mooney viscosity is measured based on the measuring method prescribed | regulated to JISK6300-1: 2013. The test is performed as follows. As a test piece to be used, a set of two test samples having a diameter of about 50 mm and a thickness of about 6 mm is prepared by a roll-through method described in JIS K 6300-1 5.3.1. A disk-shaped metal L-shaped rotor is mounted in a cylindrical hollow portion (cavity) composed of two dies, and the rubber test piece obtained therein is filled. Thereafter, the rotor is rotated under constant conditions of a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a test temperature of 125 ° C., and the torque applied to the rotor by the rubber resistance at this time is measured in Mooney units as the Mooney viscosity of the rubber.

  The ethylene-α olefin rubber has an ethylene constituent amount (referred to as ethylene content) in the copolymer of less than 45 to 65% by mass and preferably 48 to 62% by mass in terms of tensile strength and compression set. 50 to 60% by mass is more preferable. The ethylene content is a value measured according to the method described in ASTM D3900.

The ethylene-α olefin rubber is a rubber made of an ethylene-α olefin copolymer, preferably a rubber made of a binary copolymer of ethylene and α-olefin, and ethylene, α-olefin and diene. Examples thereof include rubber made of a terpolymer. The diene of the terpolymer may be a conjugated diene or a non-conjugated diene, and is preferably a non-conjugated diene. That is, examples of the ternary copolymer include a ternary copolymer of ethylene, an α-olefin, and a conjugated diene, and a terpolymer of ethylene, an α-olefin, and a nonconjugated diene. Preferred are binary copolymers of ethylene and α-olefins and terpolymers of ethylene, α-olefins and non-conjugated dienes.
Examples of the conjugated diene include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and the like, and butadiene is preferable. Non-conjugated dienes include, for example, dicyclopentadiene (DCPD), ethylidene norbornene (ENB), 1,4-hexadiene, and ethylidene norbornene is preferred. Each component of a conjugated diene compound and a non-conjugated diene is used individually by 1 type, or can use 2 or more types together.
Preferred examples of the α-olefin include α-olefins having 3 to 12 carbon atoms. The α-olefin is not particularly limited, and examples thereof include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and 1-dodecene.

  Examples of the rubber composed of a binary copolymer of ethylene and α-olefin include ethylene-propylene rubber, ethylene-butene rubber, and ethylene-octene rubber. Examples of the rubber made of a terpolymer of ethylene, α-olefin and diene include ethylene-propylene-diene rubber and ethylene-butene-diene rubber. Among these, ethylene-propylene rubber, ethylene-butene rubber, ethylene-propylene-diene rubber and ethylene-butene-diene rubber are preferable, ethylene-propylene rubber and ethylene-propylene-diene rubber are more preferable, ethylene-propylene rubber or ethylene-propylene-ethylidene. Norbornene rubber is particularly preferred.

The ethylene-α olefin rubber has a diene component content (referred to as diene content) in the copolymer of preferably 0 to 10 mass%, more preferably 0 to 5 mass%, and even more preferably 0 to 4 mass%. If diene content is the range of 0-10 mass%, the reactivity will not become high too much and the moldability in a process (2) can be hold | maintained. The diene content can be measured by, for example, infrared absorption spectroscopy (FT-IR), proton NMR ( ¹ H-NMR) method or the like.

  Content of ethylene-alpha olefin rubber is 61-100 mass parts in 100 mass parts of base rubber. When the content of the ethylene-α olefin rubber is 61 parts by mass or more, the above excellent characteristics can be imparted to the molded body. In the present invention, the content of the ethylene-α-olefin rubber is preferably 70 to 99 parts by mass, more preferably 75 to 95 parts by mass, and more preferably 80 to 95 parts by mass in 100 parts by mass of the base rubber in terms of moldability and compression set. 90 parts by mass is more preferable.

  One type of ethylene-α-olefin rubber may be used alone, or two or more types may be used in combination.

(Polypropylene resin)
A polypropylene resin (PP) will not be specifically limited if it is resin which consists of a polymer which contains a propylene component as a structural component. Polypropylene resins include propylene homopolymer (h-PP), random polypropylene (r-PP) which is a copolymer with a small amount of ethylene and / or 1-butene, and rubber such as ethylene rubber. -Block polypropylene (b-PP) and the like dispersed in PP and r-PP are included. Among these, random polypropylene is preferable.
Although the melt flow rate (MFR, 230 degreeC, 21.18N) of a polypropylene resin is not specifically limited, 0.5-50 g / 10min is preferable, Most preferably, it is 10-30 g / 10min. By using an MFR polypropylene resin in this range, a molded article with excellent appearance can be obtained while further imparting high-speed moldability. MFR (190 ° C., 21.18 N) is a value measured under condition D of 190 ° C. and 21.18 N based on “Method A (manual cut-off method)” defined in JIS K 7210.
As PP, for example, Novatec (registered trademark) PP (manufactured by Nippon Polypro Co., Ltd.), PM940M, PM921V (all are trade names, manufactured by Sun Allomer Co., Ltd.), Sumitomo Noblen (registered trademark, manufactured by Sumitomo Chemical Co., Ltd.), and Prime Polypro (registered) Trademark, manufactured by Prime Polymer Co., Ltd.).
When the base rubber contains a polypropylene resin, the content of the polypropylene resin is not particularly limited, but is preferably 1 to 30 parts by mass, and 5 to 25 parts by mass in 100 parts by mass of the base rubber. Is more preferable, and 10 to 20 parts by mass is even more preferable.

  A polypropylene resin may be used individually by 1 type, and may use 2 or more types together.

<Inorganic filler>
The inorganic filler used in the present invention can be used without particular limitation as long as it has a site that can be chemically bonded to the reaction site of the silane coupling agent by hydrogen bonding or covalent bonding. Examples of the site that can be chemically bonded to the reaction site of the silane coupling agent in this inorganic filler include OH groups (hydroxy groups, water molecules containing water or water of crystal water, OH groups such as carboxy groups), amino groups, and SH groups. It is done.

Examples of such inorganic fillers include metal hydrates such as compounds having hydrated water, hydroxyl groups or crystal water. Examples of the metal hydrate include metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and further calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, and aluminum nitride. In addition to aluminum borate whisker and the like, inorganic acid salts or inorganic oxides such as hydrated aluminum silicate, hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite and the like having hydrated water and the like can be mentioned.
In addition to metal hydrates, examples of the inorganic filler include boron nitride, silica (crystalline silica, amorphous silica, etc.), carbon black, clay, zinc oxide, tin oxide, titanium oxide, molybdenum oxide, three Antimony oxide, silicone compound, quartz, talc, zinc borate, white carbon, zinc borate, hydroxy hydroxystannate, zinc stannate.
Among these, the inorganic filler is preferably at least one selected from the group consisting of metal hydrate, talc, clay, silica, and carbon black.
An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

  The average primary particle size of the inorganic filler is preferably 0.001 to 10 μm, more preferably 0.005 to 5 μm, still more preferably 0.01 to 2 μm, and particularly preferably 0.015 to 1 μm. When the average primary particle size is within the above range, the retention effect of the silane coupling agent is high, and the tensile strength and compression set are excellent. Further, the inorganic filler hardly aggregates when mixed with the silane coupling agent, and the appearance is excellent. The average primary particle size is determined by an optical particle size analyzer such as a laser diffraction / scattering particle size distribution measuring device after being dispersed with alcohol or water.

  As the inorganic filler, a surface-treated inorganic filler surface-treated with a silane coupling agent or the like can be used. Examples of the silane coupling agent surface-treated inorganic filler include Kisuma 5L, Kisuma 5P (both trade names, magnesium hydroxide, manufactured by Kyowa Chemical Co., Ltd.) and aluminum hydroxide. The surface treatment amount of the inorganic filler with the silane coupling agent is not particularly limited, but is, for example, 2% by mass or less.

<Silane coupling agent>
The silane coupling agent used in the present invention is a chemical bond between a grafting reaction site (group or atom) that can be grafted to the base rubber in the presence of radicals generated by the decomposition of an organic peroxide and an inorganic filler. It is sufficient to have at least a reactive site (including a site generated by hydrolysis, such as a silyl ester group) that can be reacted with a reactive site and capable of silanol condensation. As such a silane coupling agent, a hydrolyzable silane coupling agent having a hydrolyzable group at the terminal is preferable. More preferably, the silane coupling agent has an amino group, a glycidyl group or an ethylenically unsaturated group-containing group and a hydrolyzable group-containing group at the terminal, and more preferably ethylene at the terminal. It is a silane coupling agent having a group containing a polymerizable unsaturated group and a group containing a hydrolyzable group. Although it does not specifically limit as group containing an ethylenically unsaturated group, For example, a vinyl group, an allyl group, a (meth) acryloyloxy group, a (meth) acryloyloxyalkylene group, p-styryl group etc. are mentioned. Moreover, you may use together these silane coupling agents and the silane coupling agent which has another terminal group.

  As such a silane coupling agent, for example, a compound represented by the following general formula (1) can be used.

In general formula (1), R _a11 is a group containing an ethylenically unsaturated group, and R _b11 is an aliphatic hydrocarbon group, a hydrogen atom, or Y ¹³ . Y ¹¹ , Y ¹² and Y ¹³ are hydrolyzable organic groups. Y ¹¹ , Y ¹² and Y ¹³ may be the same as or different from each other.

R _a11 of the silane coupling agent represented by the general formula (1) is preferably a group containing an ethylenically unsaturated group, and the group containing an ethylenically unsaturated group is as described above, preferably vinyl. It is a group.

R _b11 is an aliphatic hydrocarbon group, a hydrogen atom, or Y ¹³ to be described later. The aliphatic hydrocarbon group is a monovalent aliphatic hydrocarbon group having 1 to 8 carbon atoms excluding the aliphatic unsaturated hydrocarbon group. Is mentioned. R _b11 is preferably Y ¹³ described later.

Y ¹¹ , Y ¹² and Y ¹³ are hydrolyzable organic groups such as an alkoxy group having 1 to 6 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, and an acyloxy group having 1 to 4 carbon atoms. And an alkoxy group is preferred. Specific examples of the hydrolyzable organic group include methoxy, ethoxy, butoxy, acyloxy and the like. Among these, methoxy or ethoxy is more preferable, and methoxy is particularly preferable from the viewpoint of the reactivity of the silane coupling agent.

The silane coupling agent is preferably a silane coupling agent having a high hydrolysis rate, more preferably R _b11 is Y ¹³ and Y ¹¹ , Y ¹² and Y ¹³ are the same as each other. Or a hydrolyzable silane coupling agent in which at least one of Y ¹¹ , Y ¹² and Y ¹³ is a methoxy group, more preferably R _b11 is Y ¹³ and Y ¹¹ , Y ¹² and Y ¹³ are Silane coupling agents that are the same as each other. Particularly preferred are hydrolyzable silane coupling agents, all of which are methoxy groups.

Specific examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinyldimethoxyethoxysilane, vinyldimethoxybutoxysilane, vinyldiethoxybutoxysilane, allyltrimethoxysilane, allyltrimethoxysilane. Examples thereof include vinyl silanes such as ethoxysilane and vinyltriacetoxysilane, and (meth) acryloxysilanes such as methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, and methacryloxypropylmethyldimethoxysilane.
Those having a glycidyl group at the end include 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like.
Among the silane coupling agents, a silane coupling agent having a vinyl group and an alkoxy group at the terminal is more preferable, and vinyltrimethoxysilane and vinyltriethoxysilane are particularly preferable.

  A silane coupling agent may be used individually by 1 type, and may use 2 or more types together. Further, it may be used as it is or diluted with a solvent or the like.

<Organic peroxide>
The organic peroxide generates radicals by at least thermal decomposition and performs grafting reaction by radical reaction (including hydrogen radical abstraction reaction from rubber) between the grafting reaction site of the silane coupling agent and the base rubber as a catalyst. Work to raise.
The organic peroxide is not particularly limited as long as it generates radicals. For example, the general formula: R ¹ —OO—R ² , R ³ —OO—C (═O) R ⁴ , R ⁵ C A compound represented by (═O) —OO (C═O) R ⁶ is preferred. Here, R ^{1 to} R ⁶ each independently represents an alkyl group, an aryl group, or an acyl group. Among R ^{1 to} R ⁶ of each compound, those in which all are alkyl groups or those in which any one is an alkyl group and the remainder is an acyl group are preferable.

  Examples of such organic peroxides include dicumyl peroxide (DCP), di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, , 5-Dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3 , 3,5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxide Oxybenzoate, tert-butyl peroxyisopropyl carbonate, diace Peroxide, lauroyl peroxide, may be mentioned tert- butyl cumyl peroxide and the like. Of these, dicumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5-dimethyl-2 are preferable in terms of odor, colorability, and scorch stability. , 5-Di- (tert-butylperoxy) hexyne-3 is preferred.

The decomposition temperature of the organic peroxide is preferably from 130 to 195 ° C, particularly preferably from 150 to 185 ° C.
In the present invention, the decomposition temperature of an organic peroxide means that when an organic peroxide having a single composition is heated, it is itself half decomposed into two or more compounds at a certain temperature or temperature range for 1 minute. It means the temperature at which the reaction takes place (1 minute half-life temperature). Specifically, it refers to the temperature at which heat absorption or heat generation starts when heated from room temperature in a nitrogen gas atmosphere at a rate of temperature increase of 5 ° C./min by thermal analysis such as DSC method.

<Silanol condensation catalyst>
The silanol condensation catalyst functions to cause a condensation reaction of the silane coupling agent grafted on the base rubber in the presence of moisture. Based on the action of the silanol condensation catalyst, the rubbers are cross-linked through a silane coupling agent. As a result, it has excellent tensile strength and small compression set (hereinafter sometimes referred to as “excellent compression set”) without using vulcanization equipment, and can be molded at high temperature and high speed as necessary. A silane-crosslinked rubber molded article can be obtained in a shorter time than the rubber production method.

  Examples of the silanol condensation catalyst used in the present invention include organotin compounds, metal soaps, platinum compounds and the like. Common silanol condensation catalysts include, for example, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, zinc stearate, lead stearate, barium stearate, calcium stearate, sodium stearate, naphthenic acid Lead, lead sulfate, zinc sulfate, organic platinum compounds and the like are used. Among these, organic tin compounds such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctiate, and dibutyltin diacetate are particularly preferable.

<Carrier rubber>
The silanol condensation catalyst is used by mixing with rubber as desired. Such rubber (also referred to as carrier rubber) is not particularly limited, and each rubber component or each resin component described as the base rubber can be used.

<Additives>
The silane cross-linked rubber molded product and the silane cross-linkable rubber composition may contain various additives generally used in the rubber product as long as the effects of the present invention are not impaired. Examples of such additives include crosslinking aids, antioxidants, lubricants, colorants, metal deactivators, and fillers (including flame retardant (auxiliary) agents) other than the above inorganic fillers. It is done.

Next, the silane crosslinkable rubber composition and the method for producing the silane crosslinkable rubber molded product of the present invention will be specifically described.
Each of the “method for producing a silane-crosslinked rubber molded product” and the “method for producing a silane-crosslinkable rubber composition” of the present invention performs at least the following step (1). Therefore, the “method for producing a silane-crosslinked rubber molded product” of the present invention and the “method for producing a silane-crosslinkable rubber composition” of the present invention will be described together below (in the description common to both production methods, the present invention May be referred to as a manufacturing method.)

Step (1): 0.3 to 150 parts by mass of an inorganic filler, 1 to 15 parts by mass of a silane coupling agent, and 0.01 to 0.6 parts by mass of an organic peroxide with respect to 100 parts by mass of the base rubber Step of melting and mixing 0.0001 to 0.5 parts by mass of silanol condensation catalyst to obtain a silane crosslinkable rubber composition as a molten mixture Step (2): Silane crosslinkable rubber composition obtained in step (1) Step of molding a product to obtain a molded body Step (3): Step of obtaining a silane-crosslinked rubber molded body by contacting the molded body obtained in step (2) with water

When this step (1) melts and mixes all of the base rubber in step (a), it has steps (a) and (c), and melts and mixes part of the base rubber in the following step (a) When doing, it has a process (a), a process (b), and a process (c).
Step (a): All or part of the base rubber, the inorganic filler, the silane coupling agent, and the organic peroxide are melt-mixed at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and a silane master batch is prepared. Step (b): Step of preparing a catalyst master batch by melt-mixing the remainder of the base rubber and the silanol condensation catalyst Step (c): A silane master batch and a silanol condensation catalyst or the catalyst master batch. Step of melting and mixing Here, mixing means obtaining a uniform mixture.

  In the production method of the present invention, the “base rubber” is a base rubber for forming a silane cross-linked rubber molded product or a silane cross-linkable rubber composition. Therefore, in the production method of the present invention, the silane crosslinkable rubber composition obtained in step (1) only needs to contain 100 parts by mass of the base rubber. For example, in the step (a), “a mode in which the total amount (100 parts by mass) of the base rubber is blended” and “a mode in which a part of the base rubber is blended” are included. In the “embodiment in which a part of the base rubber is blended”, the remainder of the base rubber may be mixed as a carrier rubber in the step (b).

In the present invention, “part of the base rubber” is a rubber used in the step (a) of the base rubber, and a part of the base rubber itself (having the same composition as the base rubber) constitutes the base rubber. Part of the component (rubber component or resin component) to be used, and part of the component constituting the base rubber (for example, the total amount of a specific component among a plurality of components).
In addition, the “remaining part of the base rubber” is the remaining rubber excluding a part of the base rubber used in the step (a), specifically, the remaining part of the base rubber itself (the same composition as the base rubber). The remainder of the components constituting the base rubber and the remaining components constituting the base rubber.

When a part of the base rubber is blended in the step (a), the content of 100 parts by weight of the base rubber in the step (1) is the total amount of each component mixed in the step (a) and the step (b). .
Here, when the remainder of the base rubber is blended in the step (b), the base rubber is preferably blended in the step (a), preferably 80 to 99 parts by mass, more preferably 94 to 98 parts by mass. In b), preferably 1 to 20 parts by mass, more preferably 2 to 6 parts by mass are blended.

  In the step (1), the content of the ethylene-α olefin rubber and the polypropylene resin in the base rubber is as described above. By adding a polypropylene resin, molding can be performed at a higher linear velocity while achieving excellent tensile strength and compression set.

  In the step (1), the content of the organic peroxide is 0.01 to 0.6 parts by mass, preferably 0.1 to 0.5 parts by mass with respect to 100 parts by mass of the base rubber. When the content of the organic peroxide is less than 0.01 parts by mass, the grafting reaction does not proceed at the time of melt mixing, and the silane coupling agents are condensed with each other to obtain sufficient tensile strength and excellent compression set. There are times when you can't. On the other hand, when the amount exceeds 0.6 parts by mass, many of the base rubbers are directly cross-linked by side reactions to form bumps, resulting in poor appearance. Thus, by setting the content of the organic peroxide within this range, a grafting reaction can be carried out in an appropriate range, and a composition excellent in moldability without causing gelled flaws. Obtainable.

  Content of an inorganic filler is 0.3-150 mass parts with respect to 100 mass parts of base rubbers, 1-100 mass parts is preferable and 3-100 mass parts is more preferable. When the content of the inorganic filler is less than 0.3 part by mass, the silane coupling agent is easily volatilized, the crosslinking reaction of the silane coupling agent does not proceed, and a small compression set is obtained when a silane crosslinked rubber molded product is obtained. It may not be possible. On the other hand, when the amount exceeds 150 parts by mass, the interaction between the rubbers becomes small and the inherent properties of the rubber are impaired, so that flexibility may not be obtained.

Content of a silane coupling agent is 1-15 mass parts with respect to 100 mass parts of base rubber, Preferably it is 3-15 mass parts, More preferably, it exceeds 4 mass parts and is 15 mass parts or less. More preferably, it is more than 4 parts by mass and 10 parts by mass or less.
When the content of the silane coupling agent is less than 1 part by mass, the crosslinking reaction does not proceed sufficiently, and a small compression set may not be obtained. Moreover, there are cases where the tensile strength cannot be obtained. On the other hand, if it exceeds 15 parts by mass, the silane coupling agent cannot be completely adsorbed on the surface of the inorganic filler, and the silane coupling agent volatilizes during kneading, which is not economical. Moreover, the silane coupling agent which does not adsorb | suck condenses, and there exists a possibility that an external appearance may deteriorate by producing a spot and burning in a molded object.

  When the content of the silane coupling agent is 3 to 15 parts by mass, particularly more than 4 parts by mass and 15 parts by mass or less, both the crosslinking reaction between the base rubbers and the condensation reaction between the silane coupling agents are performed. A silane-crosslinked rubber molded article having a beautiful appearance can be produced.

Although the details of the mechanism are not yet clear, it can be considered as follows.
That is, in the step (a), when the silane coupling agent is grafted to the base rubber, the reaction by the decomposition of the organic peroxide causes the cross-linking of the base rubbers when the content of the silane coupling agent exceeds 4 parts by mass. The grafting reaction between the silane coupling agent and the base rubber and the condensation reaction between the silane coupling agents, which are faster than the reaction rate, are dominant. Therefore, the cross-linking reaction between the rubbers which causes rough appearance and bumps is less likely to occur. Thus, the cross-linking reaction between the base rubbers can be effectively suppressed according to the content of the silane coupling agent. Thereby, the external appearance at the time of shaping | molding becomes favorable. Moreover, since the said defect by the crosslinking reaction of base rubbers decreases, even if it restarts after stopping an extruder, it becomes difficult to generate | occur | produce an appearance defect. Thus, the cross-linking reaction between the base rubbers can be suppressed, and a silane cross-linked rubber molded article having a good appearance can be produced.
On the other hand, in the step (a), the condensation reaction between silane coupling agents also has a high reaction rate. However, since many silane coupling agents are fixed by being bonded or adsorbed to the inorganic filler, the condensation reaction between the silane coupling agents bonded or adsorbed to the inorganic filler hardly occurs. The condensation reaction between the free silane coupling agents may occur without binding or adsorbing to the inorganic filler, but in the present invention, most of the silane coupling agent is bonded or adsorbed to the inorganic filler, It does not lead to the generation of gel-like spots.
As described above, it is considered that a silane-crosslinked rubber molded article having a clean appearance can be produced by using a specific amount of the silane coupling agent.

  Content of a silanol condensation catalyst is 0.0001-0.5 mass part with respect to 100 mass parts of base rubbers, Preferably it is 0.001-0.3 mass part. When the content of the silanol condensation catalyst is 0.0001 to 0.5 parts by mass, the crosslinking reaction by the condensation reaction of the silane coupling agent tends to proceed almost uniformly, and the appearance, tensile strength and compression permanent of the silane crosslinked rubber molded product Distortion is excellent and productivity is improved. That is, if the content of the silanol condensation catalyst is too small, sufficient tensile strength or excellent compression set may not be obtained. On the other hand, if the amount is too large, the crosslinking reaction due to the condensation reaction of the silane coupling agent becomes uneven, and the appearance and productivity may be inferior.

  In the step (a), all or a part of the base rubber, the inorganic filler, the silane coupling agent, and the organic peroxide are charged into the mixer at the above contents, and the decomposition temperature of the organic peroxide A silane master batch is prepared by melting and kneading while heating to the above temperature.

The temperature at which the above components are melt mixed (also referred to as melt kneading or kneading) is equal to or higher than the decomposition temperature of the organic peroxide, preferably the decomposition temperature of the organic peroxide + (1 to 80) ° C. Although it is difficult to determine the temperature of melt mixing uniquely, when it gives an example, 80-250 degreeC is preferable and 100-240 degreeC is more preferable. This decomposition temperature is preferably set after the base rubber is melted. When the mixing temperature is within the above range, the above components are melted, the organic peroxide is decomposed, and the necessary grafting reaction proceeds sufficiently in step (a). Other conditions can be set as appropriate. For example, the mixing time may be a time during which the grafting reaction of the silane coupling agent to the polyolefin resin sufficiently proceeds at the melting temperature, and is preferably, for example, 5 minutes to 1 hour.
The mixing method is not particularly limited as long as it is a method usually used for rubber, plastic and the like. The mixing device is appropriately selected according to, for example, the content of the inorganic filler. As the kneading apparatus, a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, various kneaders, or the like is used. A closed mixer such as a Banbury mixer or various kneaders is preferable in terms of rubber dispersibility and stability of the crosslinking reaction.
When the inorganic filler is mixed in excess of 100 parts by mass with respect to 100 parts by mass of the base rubber, it is preferable to melt and mix with a continuous kneader, a pressure kneader, or a Banbury mixer.

In the present invention, “all or part of the base rubber, the organic peroxide, the inorganic filler, and the silane coupling agent are melt-mixed” does not specify the order of mixing at the time of melt-mixing. It means that they may be mixed in order. That is, the mixing order in the step (a) is not particularly limited.
Also, the method for mixing rubber is not particularly limited. For example, rubber prepared and mixed in advance may be used, and each rubber component or resin component may be separately mixed.

In the step (a), each of the above components can be melt-mixed at a time, but preferably, the silane coupling agent is not mixed with the silane masterbatch alone, but is mixed in a premixed state with an inorganic filler. Can also be done. The premixed silane coupling agent is present so as to surround the surface of the inorganic filler, and part or all of the silane coupling agent is adsorbed or bonded to the inorganic filler. Thereby, volatilization of the silane coupling agent can be reduced during subsequent melt mixing. Moreover, it is possible to prevent the silane coupling agent that is not adsorbed or bonded to the inorganic filler from condensing and becoming difficult to melt and mix. Furthermore, a desired shape can be obtained during extrusion molding.
As such a mixing method, the organic peroxide, the inorganic filler, and the silane coupling agent are preferably used at a temperature lower than the decomposition temperature of the organic peroxide, preferably at room temperature (25 ° C.), preferably about 1 to 10 minutes. And a method of melt-mixing the obtained mixture and the base rubber after premixing (dispersing).

The method of mixing the inorganic filler, the silane coupling agent and the organic peroxide is not particularly limited, and the organic peroxide may be mixed with the inorganic filler or the like, or the inorganic filler and the silane coupling agent. May be mixed in any of the mixing stages.
For example, the organic peroxide may be mixed with the inorganic filler after being mixed with the silane coupling agent, or may be separately mixed with the inorganic filler separately from the silane coupling agent. In the present invention, it is better to mix the organic peroxide and the silane coupling agent substantially together. On the other hand, depending on production conditions, only the silane coupling agent may be mixed with the inorganic filler, and then the organic peroxide may be mixed. That is, in the step (1), an inorganic filler previously mixed with a silane coupling agent can be used.
The organic peroxide may be mixed with other components or may be a simple substance.
In the mixing method of the organic peroxide, the inorganic filler, and the silane coupling agent, a rubber component or a resin component may be present as long as the temperature below the decomposition temperature is maintained.

Examples of the mixing method of the inorganic filler, the silane coupling agent, and the organic peroxide include mixing methods such as wet processing and dry processing. Specifically, a wet process in which a silane coupling agent is added in a state where an inorganic filler is dispersed in a solvent such as alcohol or water, a dry process in which both are added by heating or non-heating, and both are mentioned. In the present invention, dry processing is preferred in which a silane coupling agent is added to an inorganic filler, preferably a dried inorganic filler, with heating or non-heating and mixed.
This premixing is preferably performed with a mixer-type kneader such as a Banbury mixer or a kneader. In this way, excessive crosslinking reaction between the base rubbers can be prevented, and the appearance becomes excellent. The premixing may be performed using a mixer such as a Henschel mixer, or may be performed manually.
In wet mixing, the silane coupling agent and the inorganic filler have a strong bond, so that the volatilization of the silane coupling agent can be effectively suppressed, but the grafting reaction to the base rubber may be difficult to proceed. is there. On the other hand, in the dry mixing, the binding force between the inorganic filler and the silane coupling agent becomes relatively weak, so that the grafting reaction efficiently proceeds and the silanol condensation reaction easily proceeds.

  In the premixing method, the obtained mixture and the base rubber are then melt-kneaded while being heated to the decomposition temperature of the organic peroxide or higher.

  In the step (a), it is preferable to knead the above-mentioned components without substantially mixing the silanol condensation catalyst. Thereby, the condensation reaction of a silane coupling agent can be suppressed, it is easy to melt and mix, and a desired shape can be obtained during extrusion molding. Here, “substantially not mixed” does not exclude the unavoidably existing silanol condensation catalyst, and is present to such an extent that the above-mentioned problem due to silanol condensation of the silane coupling agent does not occur. Means good. For example, in the step (a), the silanol condensation catalyst may be present as long as it is 0.01 part by mass or less with respect to 100 parts by mass of the base rubber.

  In the step (1), the above-mentioned additives, particularly the antioxidant and the metal deactivator may be mixed in any step or component, but are preferably mixed in the carrier rubber. For example, when an antioxidant is added in a large amount (for example, 1 part by mass or more) to a silane masterbatch, crosslinking inhibition occurs due to a radical scavenging effect, and as a result, the grafting reaction may not proceed sufficiently.

  Thus, a process (a) is performed and a silane masterbatch (it is also called silane MB) is prepared. As will be described later, this silane MB is preferably used together with a silanol condensation catalyst or a catalyst master batch described later in the production of the mixture (silane crosslinkable rubber composition) prepared in step (1). Silane MB contains a silane crosslinkable rubber (silane graft rubber) in which a silane coupling agent is grafted to the base rubber to such an extent that it can be molded by the step (2) described later.

  Next, in the production method of the present invention, when part of the base rubber is melt-mixed in the step (a), the remainder of the base rubber and the silanol condensation catalyst are melt-mixed to form a catalyst master batch (also referred to as catalyst MB). Step (b) is prepared. Therefore, when all the base rubber is melt-mixed in the step (a), the step (b) may not be performed, and another resin and a silanol condensation catalyst may be mixed.

The mixing ratio of the rubber as the carrier rubber and the silanol condensation catalyst is not particularly limited, but is preferably set so as to satisfy the above content in the step (1).
The mixing may be a method capable of uniformly mixing, and includes mixing (melting mixing) performed under melting of rubber. The melt mixing can be performed in the same manner as the melt mixing in the step (a). For example, the mixing temperature can be 80 to 250 ° C, more preferably 100 to 240 ° C. Other conditions such as the mixing time can be set as appropriate.

In the step (b), another rubber component or resin component can be used as the carrier rubber instead of or in addition to the remainder of the base rubber. That is, in the step (b), the remainder of the base rubber when a part of the base rubber is melt-mixed in the step (a), or a rubber component or a resin component other than the base rubber used in the step (a), and silanol The catalyst MB may be prepared by melt mixing with a condensation catalyst.
When the carrier rubber is another rubber component or resin component, the content of the other rubber component or resin component can be promoted quickly in the step (a), and in addition, it is less likely to cause blistering during molding. Is preferably 1 to 50 parts by mass, more preferably 2 to 30 parts by mass, and even more preferably 4 to 20 parts by mass with respect to 100 parts by mass of the base rubber.

  Moreover, you may use an inorganic filler in a process (b). In this case, although content of an inorganic filler is not specifically limited, 350 mass parts or less are preferable with respect to 100 mass parts of carrier rubber. When the content of the inorganic filler is large, the silanol condensation catalyst is difficult to disperse and the crosslinking reaction is difficult to proceed.

The catalyst MB prepared in this way is a mixture of a silanol condensation catalyst, a carrier rubber, and an inorganic filler that is optionally added.
The catalyst MB is used as a master batch set together with the silane MB in the production of the silane crosslinkable rubber composition prepared in the step (1).

Next, in the production method of the present invention, the step (c) is performed in which the silane MB and the silanol condensation catalyst or the catalyst MB are mixed to obtain a molten mixture.
The mixing method may be any mixing method as long as a uniform molten mixture can be obtained as described above.

  The mixing is basically the same as the melt mixing in step (a). Mixing is carried out at a temperature at which the base rubber and other resin components melt. The mixing temperature is appropriately selected according to the melting temperature of the base rubber or carrier rubber. In the step (c), the mixing temperature is, for example, preferably 100 to 250 ° C, more preferably 120 to 220 ° C. Other conditions such as mixing (kneading) time can be set as appropriate.

  In the step (c), in order to avoid silanol condensation reaction, it is preferable that the silane MB and the silanol condensation catalyst are not mixed and kept at a high temperature for a long time.

  This step (c) may be any step as long as the silane MB and the silanol condensation catalyst are mixed to obtain a molten mixture, and the silanol condensation catalyst and the catalyst MB containing the carrier rubber and the silane MB are melt mixed. Is preferred.

In this way, the steps (a) to (c) (step (1)), that is, the method for producing the silane crosslinkable rubber composition of the present invention is performed, and the silane crosslinkable rubber composition of the present invention is obtained as a molten mixture. Manufactured. This silane crosslinkable rubber composition has a Mooney viscosity (ML (1 + 4) 125 ° C.) measured in accordance with JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of less than 45 to 65% by mass. A silane crosslinkable rubber obtained by grafting a silane coupling agent to a base rubber containing 61 to 100% by mass of ethylene-α-olefin rubber, and 0.3 to 150 parts by mass of an inorganic filler with respect to 100 parts by mass of the base rubber, Containing 0.0001 to 0.5 parts by mass of a silanol condensation catalyst.
The silane crosslinkable rubber contained in the silane crosslinkable rubber composition is a silane crosslinkable rubber in which a silane coupling agent is grafted onto a base rubber. In this silane crosslinkable rubber, the reaction site of the silane coupling agent may be bonded or adsorbed to the inorganic filler, but is not silanol condensed as described later. Therefore, the silane crosslinkable rubber is a crosslinkable rubber in which a silane coupling agent bonded or adsorbed to an inorganic filler is grafted to the base rubber, and a crosslink in which a silane coupling agent not bonded to or adsorbed to the inorganic filler is grafted to the base rubber. At least. The silane crosslinkable rubber may have a silane coupling agent to which an inorganic filler is bonded or adsorbed and a silane coupling agent to which an inorganic filler is not bonded or adsorbed. Moreover, the silane coupling agent and the unreacted rubber component may be included.

The silane cross-linkable rubber has an Mooney viscosity (ML (1 + 4) 125 ° C.) measured in accordance with JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of less than 45 to 65% by mass. A rubber obtained by grafting reaction of 70 to 100% by mass of 1 to 15 parts by mass of a silane coupling agent with 100 parts by mass of base rubber containing 61 to 100% by mass of olefin rubber.
The reaction rate of the silane coupling agent when the silane coupling agent is grafted to the base rubber (also referred to as grafting rate) is not particularly limited as long as the effect of the present invention is not impaired. In the present invention, it is difficult to uniquely determine the grafting rate. For example, the grafting rate by the measuring method described in the examples described later is preferably 70 to 100% by mass, and 75 to 100%. It is more preferable that it is mass%, and it is further more preferable that it is 80-100 mass%. When the grafting rate is 70 to 100% by mass, the base rubber is sufficiently cross-linked, which is suitable for imparting the above excellent characteristics.
In the present invention, the grafting rate can be set within a predetermined range depending on the type or content of the organic peroxide, the type of silane coupling agent, the use of a closed mixer, and the like.

  The silane crosslinkable rubber obtained by the step (1) is an uncrosslinked product in which the silane coupling agent is not silanol condensed. In practice, when melt-mixed in step (c), partial cross-linking (partial cross-linking) is inevitable, but the resulting silane cross-linkable rubber composition can be molded at least in step (2). Is maintained (uncrosslinked or partially crosslinked).

  In step (1), steps (a) to (c) can be performed simultaneously or sequentially.

Next, in the method for producing a silane-crosslinked rubber molded article of the present invention, step (2) and step (3) are performed.
In the method for producing a silane-crosslinked rubber molded body of the present invention, the step (2) of molding the obtained molten mixture to obtain a molded body is performed. This process (2) should just be able to shape | mold a molten mixture, and according to the form of the product of this invention, a shaping | molding method and shaping conditions are selected suitably. Examples of the molding method include extrusion molding using an extruder, injection molding using an injection molding machine, press molding using a press molding machine, and molding using other molding machines. Extrusion is preferred when the product of the invention is a wire or fiber optic cable.
When the molding step (2) is performed by extrusion molding, the molding speed (extrusion speed) of the silane crosslinkable rubber composition of the present invention is not particularly limited, and is usually less than 1 to 20 m / min, preferably 1 at linear speed. -10 m / min. In the present invention, the molding speed can be set to a high speed of 20 to 200 m / min as a linear speed in order to further improve productivity.
Moreover, extrusion molding can also be performed at high temperature. When the molding temperature is set to a high temperature, extrusion can be easily performed at a high extrusion speed as described above. In particular, the production method of the present invention can realize an excellent appearance. In the case where the molding temperature is set to a high temperature, for example, it can be set to 150 ° C. or higher, preferably 180 to 250 ° C.

Moreover, a process (2) can be performed simultaneously with a process (c) or continuously. That is, as one embodiment of the melt mixing in the step (c), at the time of melt molding, for example, at the time of extrusion molding, or immediately before, the molding raw material of the silane MB and the silanol condensation catalyst or the catalyst MB is melt mixed. An embodiment is mentioned. For example, pellets such as dry blends may be mixed together at room temperature or high temperature and introduced into a molding machine (melt mixing), or mixed and then melt mixed, pelletized again, and then introduced into the molding machine. Also good. More specifically, it is possible to employ a series of steps in which a molding material is melt-kneaded in a coating apparatus, and then extrusion coated on the outer peripheral surface of a conductor or the like and molded into a desired shape.
In this way, a molded body of the silane crosslinkable rubber composition is obtained. Similar to the silane crosslinkable rubber composition, this molded product is partially crosslinked, but is in a partially crosslinked state that retains the moldability that can be molded in the step (2). Therefore, the silane crosslinked rubber molded product of the present invention is formed into a molded product that has been crosslinked or finally crosslinked by performing the step (3).

In the method for producing a silane-crosslinked rubber molded product of the present invention, a step of bringing the molded product obtained in the step (2) into contact with water is performed. As a result, the reaction sites of the silane coupling agent are condensed to cause a crosslinking reaction. Specifically, the reaction site is hydrolyzed to become silanol, and the hydroxyl group of silanol is condensed with the silanol condensation catalyst present in the molded body, thereby causing a crosslinking reaction. Thus, a silane-crosslinked rubber molded product in which the silane coupling agent is crosslinked by silanol condensation can be obtained.
The process itself in this step (3) can be performed by a normal method. Condensation between silane coupling agents proceeds only by leaving at room temperature. Therefore, in the step (3), it is not necessary to positively contact the molded body with water. In order to promote this cross-linking reaction, the molded body can be positively brought into contact with moisture. For example, it is possible to employ a method of positively contacting water, such as immersion in warm water, charging into a wet heat tank, exposure to high-temperature steam, and the like. In this case, pressure may be applied to allow moisture to penetrate inside. Such a technique is effective in the case of an electric wire having a large coating thickness or a molded body having a large volume.

  Thus, the manufacturing method of the silane crosslinked rubber molding of this invention is implemented, and a silane crosslinked rubber molding is manufactured from the silane crosslinking rubber composition of this invention. As will be described later, this silane cross-linked rubber molded article contains a cross-linked rubber obtained by cross-linking a silane cross-linkable rubber through a silane coupling agent. One form of this silane crosslinked rubber molding contains a silane crosslinked rubber and an inorganic filler. Here, the inorganic filler may be bonded to the silane coupling agent of the silane crosslinked rubber. Therefore, the silane crosslinked rubber is obtained by bonding or adsorbing a plurality of crosslinked rubbers to the inorganic filler by the silane coupling agent, thereby bonding (crosslinking) the crosslinked rubber via the inorganic filler and the silane coupling agent, and the above-mentioned crosslinking property. The reaction site of the silane coupling agent of the rubber hydrolyzes and undergoes silanol condensation reaction with each other, thereby containing at least a crosslinked rubber crosslinked via the silane coupling agent. Moreover, as for the silane crosslinked rubber, the bond (crosslinking) via the inorganic filler and the silane coupling agent and the crosslinking via the silane coupling agent may be mixed. Furthermore, the silane coupling agent and the unreacted rubber component and / or the uncrosslinked silane crosslinkability may be included.

The reason for grafting in the production method of the present invention is not yet clear, but is considered as follows. That is, when the base rubber is heated and kneaded at a temperature higher than the decomposition temperature of the organic peroxide together with the inorganic filler and the silane coupling agent in the presence of the organic peroxide, the organic peroxide is decomposed to generate radicals. On the other hand, grafting of the silane coupling agent occurs.
In addition, due to the heating in the above melt mixing, a chemical bond forming reaction is caused in part by a covalent bond between a silane coupling agent and a group such as a hydroxyl group on the surface of the inorganic filler.
In the present invention, the final cross-linking reaction may be performed in step (3), and if a specific amount of the silane coupling agent is blended with the base rubber as described above, extrusion processability (moldability) at the time of molding is impaired. It becomes possible to mix | blend a large amount of inorganic fillers, without. Thereby, while ensuring the outstanding moldability, it can have the outstanding external appearance of a molded object, and also a mechanical characteristic.

The method for producing a silane-crosslinked rubber molded article according to the present invention comprises a base rubber having a low Mooney viscosity and an ethylene-α olefin rubber having an ethylene content in the above range at the above content by the above silane crosslinking method. Mix, mold and crosslink. Accordingly, it is possible to produce a silane-crosslinked rubber molded article having excellent flexibility, tensile strength, compression set, and appearance.
Furthermore, since the method for producing a silane-crosslinked rubber molded product of the present invention involves molding and crosslinking the base rubber by the silane crosslinking method described above, vulcanization equipment is not required for performing the crosslinking reaction, and EP rubber is added. Productivity can be increased with respect to the sulfur process.
Furthermore, the method for producing a silane-crosslinked rubber molded body of the present invention can suppress crosslinking of the base rubber during molding, and if necessary, can set the molding temperature to a high temperature as described above, and further increase the linear velocity. It can also be set.

The mechanism of action of the above process of the present invention is not yet clear, but is estimated as follows. That is, by using an inorganic filler and a silane coupling agent before and / or during kneading with the base rubber, the silane coupling agent is bonded to a group capable of chemically bonding with the inorganic filler at the reaction site. , Retained. Alternatively, it is physically and chemically adsorbed and held in the hole or surface of the inorganic filler without being bonded to the inorganic filler. In this way, a silane coupling agent that binds to the inorganic filler with a strong bond (the reason is, for example, the formation of a chemical bond with a group capable of chemically reacting on the surface of the inorganic filler) and a weak bond. Bonding silane coupling agents (for example, interactions due to hydrogen bonds, interactions between ions, partial charges or dipoles, and effects due to adsorption can be considered) can be formed. In this state, when kneading with the base rubber in the presence of an organic peroxide, the silane coupling agent is hardly volatilized from the rubber composition (rubber kneaded material) as will be described later, and the other terminal. In the grafting reaction site existing in the base rubber, the base rubber is bonded to the site capable of grafting reaction. Thus, a silane crosslinkable rubber having a different bond to the inorganic filler and having a silane coupling agent grafted to the base rubber is formed.
In the step (1), it is considered that the diene components in the base rubber are also crosslinked by radicals generated by the decomposition of the organic peroxide. However, in the above preferred method, since the silane coupling agent, the organic peroxide, and the inorganic filler are mixed, it is considered that the grafting reaction of the silane coupling agent proceeds preferentially.

  By the above kneading, the silane coupling agent having a strong bond with the inorganic filler among the silane coupling agents is retained in the bond with the inorganic filler, and the grafting reaction site is a site where the grafting reaction of the base rubber is possible Grafting reaction with (radical site of rubber generated by abstraction of hydrogen radical by radical generated by decomposition of organic peroxide). In particular, when a plurality of silane coupling agents are bonded to the surface of one inorganic filler particle through a strong bond, a plurality of rubbers are bonded through the inorganic filler particle. By these reactions or bonds, the crosslinked network via the inorganic filler is expanded. That is, a silane crosslinkable rubber formed by grafting reaction of the silane coupling agent bonded to the inorganic filler onto the base rubber is formed.

In the case of a silane coupling agent having a strong bond with an inorganic filler, the condensation reaction in the presence of water by this silanol condensation catalyst is unlikely to occur, and the bond with the inorganic filler is retained. The reason why the silanol condensation reaction hardly occurs is considered to be that the binding energy between the inorganic filler and the silane coupling agent is very high and the condensation reaction does not occur even under the silanol condensation catalyst. Thus, the base rubber and the inorganic filler are bonded, and the rubber is crosslinked through the silane coupling agent. As a result, the adhesion between the base rubber and the inorganic filler is strengthened, and a molded article excellent in mechanical strength, tensile strength and compression set can be obtained.
In addition, a plurality of silane coupling agents can be bonded to the surface of one inorganic filler particle, and high mechanical strength can be obtained.
Thus, it is considered that the silane coupling agent bonded with a strong bond to the inorganic filler contributes to improvement of mechanical properties and tensile strength.

  On the other hand, among the silane coupling agents, the silane coupling agent having a weak bond with the inorganic filler is detached from the surface of the inorganic filler, and the grafting reaction site of the silane coupling agent is a site where the grafting reaction of the base rubber is possible. And the grafting reaction takes place. That is, a silane crosslinkable rubber is formed by grafting reaction of the silane coupling agent released from the inorganic filler onto the base rubber. The silane coupling agent in the graft portion thus produced is then mixed with a silanol condensation catalyst and brought into contact with moisture to cause a condensation reaction (crosslinking reaction). The tensile strength of the silane cross-linked rubber molded product obtained by this cross-linking reaction is increased, and it becomes possible to obtain a silane cross-linked rubber molded product having a small compression set in addition to heat resistance. Thus, it is considered that the silane coupling agent bonded with a weak bond to the inorganic filler contributes to improvement of the degree of crosslinking, that is, improvement of heat resistance and suppression of compression set.

  In particular, in the present invention, the cross-linking reaction by condensation using a silanol condensation catalyst in the presence of water in the step (3) is performed after forming the molded body. Thereby, compared with the method of performing extrusion molding and a crosslinking reaction simultaneously like the method of patent document 1, for example, the workability | operativity in the process until a molded object formation is excellent. In addition, since the condensation reaction using the silanol condensation catalyst does not proceed in an extruder having almost no moisture, extrusion at a high temperature is possible in the step (2). Therefore, molding at high temperature and high speed is also possible.

  Furthermore, when the silane coupling agent is mixed with the inorganic filler by the production method of the present invention, the appearance is excellent because the condensation of the silane coupling agents is suppressed as described above. Moreover, in the present invention, when the silane coupling agent of 3 to 15 parts by mass, particularly 4 parts by mass and 15 parts by mass or less is mixed with the inorganic filler, as described above, the process (1), particularly the process ( The cross-linking reaction between rubbers during melt kneading in a) can be effectively suppressed. Further, the silane coupling agent is bonded to the inorganic filler, and is not easily evaporated during the melt kneading in the step (1), particularly the step (a), and the reaction between the free silane coupling agents is also effective. Can be suppressed. Therefore, even if the extruder is stopped and then restarted, poor appearance hardly occurs, and a silane-crosslinked rubber molded article having a good appearance can be produced. Here, once restarting after stopping, it cannot be uniquely described depending on the composition of the base rubber, processing conditions, etc., but for example, it can be restarted at 190 ° C. for an interval of 30 minutes, preferably 90 minutes. Say.

The silane-crosslinked rubber molded article of the present invention has at least the following characteristics (measurement method is the same as in the examples) and is excellent in appearance.
That is, the compression set of the silane crosslinked rubber molded body is preferably 40% or less, more preferably 30% or less, and further preferably 20% or less. Although a minimum is not specifically limited, For example, it is 10%.
The silane cross-linked rubber molded article has a tensile strength of preferably 4 MPa or more, more preferably 6 MPa or more, and further preferably 8 MPa or more. Although an upper limit is not specifically limited, For example, it is 15 MPa.
The silane cross-linked rubber molded body has a hardness of preferably 70 or less, more preferably 60 or less, and still more preferably 50 or less as an index of flexibility. Although a minimum is not specifically limited, For example, it is 30.

  The silane cross-linkable rubber composition of the present invention can produce a silane cross-linked rubber molded article having the above-mentioned excellent characteristics. Moreover, it is excellent in high-speed moldability and exhibits high productivity.

The silane cross-linked rubber molded product of the present invention may be a product containing a silane cross-linked rubber molded product or a product consisting only of a silane cross-linked rubber molded product. Examples of the product containing the silane cross-linked rubber molded product include a product comprising a silane cross-linked rubber molded product and other members such as a support, a support frame and the like. In the present invention, the term “product” is used to include a semi-finished product, a part, and a member.
As the silane-crosslinked rubber molded article of the present invention, various industrial cables (including electric wires) coating materials, rubber molding materials (for example, automotive glass run channels, weather strips, rubber hoses, wiper blade rubbers, gaskets, anti-vibration rubbers), etc. Is mentioned.

  The silane-crosslinked rubber molded article of the present invention is preferably a product that requires any one of excellent compression set, flexibility, and high tensile strength. Such a product is not particularly limited. For example, a product requiring a compression set of 40% or less at 70 ° C., a product requiring a tensile strength of 4 MPa or more, a product requiring a hardness (flexibility) of 70 or less, or the compression set, the tensile strength, And products requiring any two or more of products requiring hardness (flexibility) of 70 or less. Specifically, as the silane-crosslinked rubber molded product of the present invention, preferably, the insulation material and sheath (cabinet material) for cabtire cables among the covering materials for various industrial cables, and further among the rubber mold materials, Examples thereof include rubber molding materials for automobiles, weather strips, gaskets, and the like.

The manufacturing method of the present invention is applied to the manufacture of components (including semi-finished products, parts, and members) that require excellent compression set, products that require strength, component parts of products such as rubber materials, or members thereof. can do.
As described above, the production method of the present invention can produce a silane-crosslinked rubber molded article having excellent characteristics as described above without requiring a vulcanization facility and with good productivity. Therefore, the production method of the present invention can be particularly preferably applied to products that require any one of excellent compression set, flexibility, and high tensile strength.

The production method of the present invention can be suitably applied to the production of electric wires and optical cables, among these products, and can form these covering materials (insulators and sheaths).
When the product of the present invention is an extrusion-molded product such as an electric wire or cable, preferably, the molding material is extruded on the outer periphery of the conductor or the like while being melt-kneaded in the extruder (extrusion coating apparatus), etc. Can be manufactured (step (c) and step (2)). Such a product uses a general-purpose extrusion coating apparatus without using a special machine such as an electron beam cross-linking machine or a rubber vulcanizing equipment, and a silane cross-linkable rubber composition in which a large amount of an inorganic filler is added. It can be molded by extrusion coating around a conductor or around a conductor that is longitudinally or twisted with tensile strength fibers. For example, a soft copper single wire or a stranded wire can be used as the conductor. In addition to the bare wire, a conductor plated with tin or an enameled insulating layer can be used as the conductor. The thickness of the insulating layer (the coating layer made of the silane crosslinkable rubber composition of the present invention) formed around the conductor is not particularly limited, but is usually about 0.15 to 5 mm.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these.
In Table 1, the numerical values related to the content of each example represent parts by mass unless otherwise specified.

  Examples 1 to 8 and Comparative Examples 1 to 11 were carried out with the following components set to the conditions shown in Table 1 using the following components.

Details of each compound (component) shown in Table 1 are shown below. Table 1 shows the Mooney viscosity (ML (1 + 4) 125 ° C.), ethylene content and diene content (measured by infrared absorption spectroscopy) of the ethylene-α-olefin rubber.
<Rubber component>
(Ethylene-α-olefin rubber, EP rubber)
"Nodel 3640" (NOREL (registered trademark), manufactured by Dow Chemical Co., ethylene-propylene-ethylidene norbornene rubber)
"EPT0045" (Mitsui EPT0045 (trade name), manufactured by Mitsui Chemicals, ethylene-propylene binary copolymer)
"EPT4045M" (Mitsui EPTM4045 (trade name), manufactured by Mitsui Chemicals, ethylene-propylene-ethylidene norbornene rubber)
"EP11" (trade name, manufactured by JSR, ethylene-propylene rubber)
"EP21" (trade name, manufactured by JSR, ethylene-propylene-ethylidene norbornene rubber)
“Vistalon 404” (trade name, manufactured by ExxonMobil, ethylene-propylene rubber)
EPM-1, EPM-2, EPM-3, and EPM-4 were synthesized by the method described later.
(Polypropylene resin)
“PM940M” (trade name, manufactured by Sun Allomer, r-PP, MFR (230 ° C., 21.18 N) 30 g / 10 min)

<Inorganic filler>
“Aerosil 200” (Aerosil (registered trademark), manufactured by Nippon Aerosil Co., Ltd., hydrophilic fumed silica, average primary particle size 12 nm)
“Crystalite 5X” (trade name, manufactured by Tatsumori, crystalline silica, average primary particle size 1.4 μm)
“Kisuma 5L” (Kisuma (registered trademark), magnesium hydroxide, manufactured by Kyowa Chemical Co., Ltd., average primary particle size 0.8 μm)

<Silane coupling agent>
"KBM1003" (trade name, manufactured by Shin-Etsu Silicone, vinyltrimethoxysilane)
<Organic peroxide>
“Perhexa 25B” (trade name, manufactured by NOF Corporation, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, half-life temperature of 179.8 ° C. for 1 minute)
<Silanol condensation catalyst>
“ADK STAB OT-1” (trade name, manufactured by ADEKA, dioctyltin dilaurate)

Synthesis of EPM-1, EPM-2, EPM-3, EPM-4 EPM-1 to 4 are pre-banbury mixers containing two or more types of EPM as shown in Table 1 so as to have Mooney viscosity and ethylene content. For 10 minutes at 150 ° C. and pelletized.
“EPM-1” (ethylene-propylene-rubber, (ML (1 + 4) 125 ° C.) = 10)
“EPM-2” (ethylene-propylene-rubber, (ML (1 + 4) 125 ° C.) = 41)
“EPM-3” (ethylene-propylene-rubber, (ML (1 + 4) 125 ° C.) = 15)
“EPM-4” (ethylene-propylene-rubber, (ML (1 + 4) 125 ° C.) = 20)

(Examples 1-8 and Comparative Examples 1-8)
In Examples 1 to 8 and Comparative Examples 1 to 8, a part (95 parts by mass) of EP rubber was used in step (a), and the remaining part (5 parts by mass) of EP rubber was used as a carrier for catalyst MB in step (b). Used as rubber.
An inorganic filler, a silane coupling agent, and an organic peroxide were mixed at a mass ratio shown in Table 1 at room temperature (25 ° C.). After melt-mixing the obtained mixture and a part of EP rubber for 5 minutes at a temperature (185 ° C.) above the decomposition temperature of the organic peroxide using a 2 L Banbury mixer (manufactured by Nippon Roll Co., Ltd.), The material was discharged at a material discharge temperature of 130 ° C. and pelletized to obtain silane MB (step (a)). The obtained silane MB contains a silane crosslinkable EP rubber obtained by grafting a silane coupling agent to an EP rubber.

  Further, the remainder of EP rubber and 0.1 part by mass of silanol condensation catalyst were melt-mixed at 150 ° C. with a Banbury mixer (manufactured by Nippon Roll Co., Ltd.) and discharged at a material discharge temperature of 130 ° C. to obtain catalyst MB ( Step (b)).

  The silane MB obtained in step (a) and the catalyst MB obtained in step (b) have an electric wire coating extruder (L / D (ratio of effective screw length L to diameter D) of 25 and a screw diameter of 25 mmφ). ), And dry blended at 25 ° C. for about 1 minute to obtain a dry blend.

-Manufacture of electric wires-
The obtained dry blended product is put into the above-mentioned extrusion molding machine for covering electric wires, and the outer diameter of a 0.8 mmφ conductor (an annealed copper wire) is finished to an outer diameter of 1.2 mmφ under the following extrusion temperature conditions. The wire precursor was manufactured by extrusion coating at a speed of 10 m / min.
Extrusion temperature conditions are divided into 3 zones C1, C2, and C3, with the temperature control in the cylinder part of the wire coating extruder from the feeder side to the die side, C1 zone is 150 ° C, C2 zone is 170 ° C, C3 zone Was set to 190 ° C, and the die temperature (molding temperature) was set to 200 ° C.
A silane crosslinkable rubber composition was prepared by melt-mixing the dry blend in an electric wire coating extruder prior to extrusion. This silane crosslinkable rubber composition contains the silane crosslinkable EP rubber, the inorganic filler and the silanol condensation catalyst having the contents shown in Table 1.
The electric wire precursor thus obtained was left in a 25 ° C., 50% RH environment for 24 hours to be brought into contact with water to produce an electric wire. This electric wire had a silane cross-linked molded article containing a silane cross-linked EP rubber cross-linked with a silane coupling agent and an inorganic filler having a content shown in Table 1 as a coating material.

−Manufacture of cylindrical rubber molded products−
In the production of the electric wire, a molten strand having a diameter of 35 mm was obtained in the same manner as in the production of the electric wire, except that a dry blend was extruded without using a conductor. Next, the melted strand was cut into a length of 15 mm, pressed into a cylindrical mold having a size of 29.0 mmφ and a thickness of 12.5 mm in the molten state, and press-preformed using a press molding machine.
Thereafter, using a press molding machine, the cylindrical mold was preheated at 170 ° C. for 10 minutes, and then the press-preformed strand was placed in a preheated mold, and press molded at 170 ° C. for 60 minutes at a pressure of 4 MPa. This produced a 29.0 mmφ, 12.5 mm thick cylindrical rubber molded product.
The cylindrical rubber molded product thus obtained was left in a 25 ° C., 50% RH environment for 24 hours to be brought into contact with water to produce a cylindrical rubber molded product. This cylindrical rubber molded product was a silane cross-linked molded article containing a silane cross-linked EP rubber obtained by cross-linking EP rubber with a silane coupling agent and an inorganic filler having a content shown in Table 1.

(Comparative Examples 9 and 10)
-Manufacture of electric wires-
The organic peroxide in the ratio shown in Table 1 was kneaded at 100 ° C. into 100 parts by mass of the conventional rubber shown in Table 1 using an 8-inch open roll, and pelletized. The obtained pellet was extrusion coated onto the conductor in the same manner as in the production of the electric wire of Example 1 using the electric wire coating extruder, thereby producing an electric wire precursor.
Here, in Comparative Examples 9 and 10, when molding was performed under the same extrusion temperature conditions as in Example 1, a cross-linking reaction occurred in the extrusion molding machine, and extrusion molding could not be performed. The appearance of the precursor was impaired. Therefore, extrusion molding was carried out by setting the C1 to C3 zones of the extruder to 90 ° C. and the die temperature to 100 ° C.
The obtained electric wire precursor was cross-linked by passing through a 20 m long chemical cross-linking tube set in a steam environment having a temperature of 200 ° C. and a pressure of 10 MPa to manufacture an electric wire.

−Manufacture of cylindrical rubber molded products−
In the production of the electric wire, a molten strand having a diameter of 35 mm was obtained in the same manner as in the production of the electric wire except that pellets were extruded without using a conductor. Next, the molten strand was cut into a length of 15 mm, pressed into a cylindrical mold having a size of 29.0 mmφ and a thickness of 12.5 mm in the molten state, and press preformed using a press molding machine.
Thereafter, using a press molding machine, the mold was preheated at 170 ° C. for 10 minutes, and then the press-preformed strand was put into a preheated mold, and press molded at 170 ° C. for 60 minutes at a pressure of 4 MPa. This produced a 29.0 mmφ, 12.5 mm thick cylindrical rubber molded product.

(Comparative Example 11)
An electric wire and a cylindrical rubber molded product were obtained in the same manner as in Example 3 except that the inorganic filler, the silane coupling agent, the organic peroxide, and the silanol condensing agent were not added.

About each obtained electric wire, the grafting rate was confirmed as follows, and the result was shown in Table 1.
In the present invention, the grafting rate of the grafting reaction of the silane coupling agent to the rubber was measured as follows. First, a test piece obtained by sampling a coating at an arbitrary position from each of the obtained electric wires was dried for 24 hours in a vacuum environment at 80 ° C., and then, from an absorption peak seen in the vicinity of 3750 cm ⁻¹ by infrared absorption spectroscopy. The mass of isolated silanol (unreacted silane coupling agent) was quantified. Next, the grafting rate was calculated from the obtained value and the mass (content) of the silane coupling agent actually used by the following formula.
Grafting rate (mass%) = {(mass actually used−isolated silanol mass by infrared absorption spectroscopy) / mass actually used) × 100

  The following tests were performed on the obtained electric wires or cylindrical rubber molded products, and the results are shown in Table 1.

<Appearance test>
The appearance of each manufactured electric wire was visually observed and evaluated. The case where the appearance of the electric wire was excellent was designated as “A”, and the case where the appearance was so severe that there was a problem on the product was designated as “B”.

<Tensile strength>
A tensile test was performed based on JIS C 3005. Tensile strength was measured at a distance between gauge points of 20 mm and a tensile speed of 200 mm / min using a tubular piece obtained by drawing a conductor from the obtained electric wire, and evaluated according to the following evaluation criteria.
The case where the tensile strength is 8 MPa or more is “A”, the case where it is 6 MPa or more and less than 8 MPa is “B”, the case where it is 4 MPa or more and less than 6 MPa is “C”, and the case where it is less than 4 MPa is “D”. "
In the present invention, the tensile strength of the evaluation “C” is a pass level of the test of the present invention.

<Flexibility>
The flexibility of the cylindrical rubber molded product produced in each example was evaluated by its hardness. That is, the hardness of each cylindrical rubber molded product was measured using a type A durometer based on JIS K 6253-3: 2012. Data reading was performed 15 seconds after the push needle was pushed.
“A” when the hardness is 50 or less, “B” when it is over 50 and 60 or less, “C” when it is over 60 and 70 or less, and “D” when it exceeds 70 It was.
In the present invention, as for the flexibility, the evaluation “C” is a passing level of the test of the present invention.

<Compression set>
Based on the JIS K 6262 A method, the compression set was measured using the cylindrical rubber molded product produced in each example. Using a compression device equipped with two compression plates and spacers (thickness is 75% of the thickness of the cylindrical rubber molded product), the cylindrical rubber molded product is compressed by 25% in the thickness direction. (Compression rate 25%), heated to 70 ° C. in this state and held for 22 hours. Thereafter, the compression was released at room temperature (23 ° C.), and after cooling for 30 minutes (final temperature was 23 ° C.), the thickness of the cylindrical rubber molded product was measured.
The compression set was calculated from the thickness of the cylindrical rubber molded product before and after compression by the following formula and evaluated according to the following evaluation criteria.
Formula: CS = [(t ₀ −t ₂ ) / (t ₀ −t ₁ )] × 100
In the formula, CS: compression set (%)
t ₀ : Thickness before compression of the cylindrical rubber molded product (original thickness) (mm)
t ₁ : Spacer thickness (mm)
t ₂ cylindrical rubber thickness after the molded product of the compression (removed from the compression device, the thickness after 30 minutes) (mm)
“A” when the compression set is 20% or less, “B” when the compression set exceeds 20% and 30% or less, “C” when the compression set exceeds 30% and 40% or less, 40 The percentage exceeding% was designated as “D”.
In the present invention, as for compression set, evaluation "C" is a pass level of the test of the present invention.

<Extrudability>
The extrusion moldability (high-speed moldability) of the silane crosslinkable rubber composition (each melt blended dry blend) prepared in each of the above examples was evaluated,
The dry blend prepared in each example was placed in an electric wire extrusion molding machine (motor load limit: 80 A) having an L / D of 25 and a screw diameter of 40 mmφ, and a 0.8 mmφ conductor according to the following extrusion temperature conditions. The wire speed was changed and extrusion coated on the outer periphery of (soft copper wire) so that the finished outer diameter was 2.4 mmφ.
As for the extrusion temperature conditions, in Examples 1 to 8 and Comparative Examples 1 to 8 and 11, the C1 zone is set to 150 ° C, the C2 zone is set to 170 ° C, the C3 zone is set to 190 ° C, and the die temperature is set to 200 ° C. did. In Comparative Examples 9 and 10, the C1 to C3 zones were set to 90 ° C and the die temperature was set to 100 ° C.
In the above-mentioned extrusion coating, high-speed moldability was evaluated according to the following evaluation criteria at the maximum production speed (maximum linear velocity) at which extrusion molding is possible. Here, the maximum production speed at which extrusion molding is possible is the linear speed at which the extruded coating does not break during the extrusion (so-called resin breakage) and the motor load does not exceed the above limit value. Shall be.
The case where the maximum linear velocity is 150 m / min or more is “A”, the case where it is 100 m / min or more and less than 150 m / min is “B”, the case where it is 50 m / min or more and less than 100 m / min is “C”. ", The case of less than 50 m / min was designated as" D ".
In the present invention, the high-speed moldability has an evaluation “C” that is a pass level of the test of the present invention.

  As is clear from the results shown in Table 1, all of the silane-crosslinked rubber molded products (electric wires or cylindrical rubber molded products) manufactured up to Examples 1 to 8 have an appearance, tensile strength, flexibility, and compression set. It was excellent. In each of the examples, extrusion molding was possible at a high temperature of 200 ° C. and a maximum linear velocity of 50 m / min or more.

In contrast, Comparative Example 1 using an EP rubber having a low Mooney viscosity (ML (1 + 4) 125 ° C.) had a low tensile strength. On the other hand, Comparative Example 2 using an EP rubber having a high Mooney viscosity (ML (1 + 4) 125 ° C.) had high hardness and insufficient flexibility.
Comparative Example 3 using EP rubber with a small amount of ethylene had low tensile strength. Comparative Example 4 using EP rubber with a large amount of ethylene had a large hardness and was not flexible enough.
Comparative Example 5 with a small content of inorganic filler had a large compression set. In Comparative Example 6 in which the content of the inorganic filler was excessive, the hardness was large and the flexibility was not sufficient.
Further, Comparative Example 7 having a low silane coupling agent content had a low tensile strength and a large compression set. Comparative Example 8 with a high content of silane coupling agent had a poor appearance.
In Comparative Examples 9 and 10 which are rubber crosslinking methods which are not silane crosslinking methods, the tensile strength was low, and even when extrusion was possible, the maximum linear velocity was slow.
Comparative Example 11 using a non-crosslinking agent had a low tensile strength and a large compression set.

As described above, the present invention can produce a silane-crosslinked rubber molded article and a silane-crosslinked rubber molded article having both excellent flexibility, high tensile strength, and small compressive strain. Further, the present invention can produce a silane cross-linked rubber molded article and a silane cross-linked rubber molded article having such excellent characteristics without requiring an EP rubber vulcanization facility, and can be molded at high temperature and high speed if necessary, and produced with high productivity. can do.

Claims (9)

  An ethylene-α olefin rubber having a Mooney viscosity (ML (1 + 4) 125 ° C.) measured in accordance with JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of 45% by mass or more and less than 65% by mass is 70. 1 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of grafting reaction to the base rubber and a reaction site capable of silanol condensation with respect to 100 parts by mass of the base rubber containing ~ 100% by mass With respect to 100 parts by mass of the silane-crosslinkable rubber grafted at a grafting rate of mass% and 100 parts by mass of the base rubber, 0.3 to 150 parts by mass of an inorganic filler, 0.0001 to 0.5 parts by mass of a silanol condensation catalyst, A silane crosslinkable rubber composition containing   The silane crosslinkable rubber composition is based on 100 parts by mass of the base rubber, 0.3 to 150 parts by mass of an inorganic filler, a grafting reaction site capable of grafting to the base rubber, and a reactive site capable of silanol condensation. 1 to 15 parts by mass of a silane coupling agent having an organic peroxide, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.0001 to 0.5 parts by mass of a silanol condensation catalyst, The silane crosslinkable rubber composition according to claim 1, wherein a rubber and the silane coupling agent are subjected to a grafting reaction.   The silane crosslinkable rubber composition according to claim 1 or 2, wherein the inorganic filler is at least one selected from the group consisting of metal hydrate, talc, clay, silica, and carbon black.   The silane crosslinkable rubber composition according to any one of claims 1 to 3, wherein the base rubber contains 1 to 30% by mass of a polypropylene resin.   The silane crosslinkable rubber composition according to any one of claims 1 to 4, wherein a content of the silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the base rubber. A silane-crosslinked rubber molded article obtained by condensing the silanol-condensable reaction site after molding the silane-crosslinkable rubber composition according to any one of claims 1 to 5.   A silane-crosslinked rubber molded article comprising the silane-crosslinked rubber molded article according to claim 6. An ethylene-α olefin rubber having a Mooney viscosity (ML (1 + 4) 125 ° C.) measured in accordance with JIS K 6300-1: 2013 of 15 to 40 and an ethylene content of 45% by mass or more and less than 65% by mass is 70. Silane cup having 0.3 to 150 parts by mass of an inorganic filler, a grafting reaction site capable of undergoing a grafting reaction on the base rubber, and a reaction site capable of silanol condensation with respect to 100 parts by mass of the base rubber containing ~ 100% by mass 1 to 15 parts by mass of a ring agent, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.0001 to 0.5 parts by mass of a silanol condensation catalyst are melt-mixed, and the base rubber and the silane cup are mixed. Silane crosslinkable rubber having step (1) of obtaining a silane crosslinkable rubber composition containing silane crosslinkable rubber by grafting reaction with a ring agent A method for producing a composition comprising:
In carrying out the step (1), when all of the base rubber is melt-mixed in the following step (a), the step (1) has the following step (a) and step (c). In the case where a part of the base rubber is melt-mixed in (a), the production of the silane crosslinkable rubber composition, wherein the step (1) has the following steps (a), (b) and (c): Method.
Step (a): All or part of the base rubber, the inorganic filler, and the silane
The pulling agent and the organic peroxide are separated from the decomposition temperature of the organic peroxide.
The base rubber and the silane coupling agent are melt mixed at the above temperature
And a silane containing a silane crosslinkable rubber
Step of preparing a master batch Step (b): Melt and mix the remaining base rubber and the silanol condensation catalyst
Step of preparing a medium master batch Step (c): The silane master batch and the silanol condensation catalyst or the catalyst matrix
A process of obtaining a silane crosslinkable rubber composition by melt mixing with a star batch A method for producing a silane-crosslinked rubber molded article having the following step (1), step (2) and step (3),
Step (1): Mooney viscosity measured based on JIS K 6300-1: 2013
(ML (1 + 4) 125 ° C.) is 15 to 40, and the ethylene content is 4
70% of ethylene-α-olefin rubber that is 5% by mass or more and less than 65% by mass
0 to 100 parts by mass of base rubber containing 100% by mass of inorganic filler 0
. 3 to 150 parts by mass and graph capable of grafting reaction to the base rubber
Silane cup having a reaction site and a reaction site capable of silanol condensation
1 to 15 parts by mass of a ring agent, 0.01 to 0.6 parts by mass of an organic peroxide,
The silanol condensation catalyst 0.0001 to 0.5 part by mass is melt mixed and
The base rubber and the silane coupling agent can be grafted.
Step of obtaining a silane crosslinkable rubber composition containing a silane crosslinkable rubber Step (2): Molding the silane crosslinkable rubber composition obtained in the step (1) to obtain a molded body.
Step (3): Silane cross-linked rubber molding by contacting the molded body obtained in the step (2) with water.
The process of obtaining the body

In carrying out the step (1), when all of the base rubber is melt-mixed in the following step (a), the step (1) has the following step (a) and step (c). In the case where a part of the base rubber is melt-mixed in (a), the production of the silane crosslinkable rubber composition, wherein the step (1) has the following steps (a), (b) and (c): Method.
Step (a): All or part of the base rubber, the inorganic filler, and the silane
The pulling agent and the organic peroxide are separated from the decomposition temperature of the organic peroxide.
The base rubber and the silane coupling agent are melt mixed at the above temperature
And a silane containing a silane crosslinkable rubber
Step of preparing a master batch Step (b): Melt and mix the remaining base rubber and the silanol condensation catalyst
Step of preparing a medium master batch Step (c): The silane master batch and the silanol condensation catalyst or the catalyst matrix
A process of obtaining a silane crosslinkable rubber composition by melt mixing with a star batch